Think again about keeping little ones so squeaky clean

Dec 08, 2009

A new Northwestern University study suggests that American parents should ease up on antibacterial soap and perhaps allow their little ones a romp or two in the mud --- or at least a much better acquaintance with everyday germs.

The study is the first to look at how microbial exposures early in life affect inflammatory processes related to diseases associated with aging in adulthood.

Most provocatively, the Northwestern study suggests that exposure to infectious microbes early in life may actually protect individuals from cardiovascular diseases that can lead to death as an adult.

"Contrary to assumptions related to earlier studies, our research suggests that ultra-clean, ultra-hygienic environments early in life may contribute to higher levels of inflammation as an adult, which in turn increases risks for a wide range of diseases," said Thomas McDade, lead author of the study, associate professor of anthropology in Northwestern's Weinberg College of Arts and Sciences and a faculty fellow at the Institute for Policy Research.

Relatively speaking, humans only recently have lived in such hyper-hygienic environments, he stressed.

The research suggests that inflammatory systems may need a higher level of exposure to common everyday bacteria and microbes to guide their development. "In other words, inflammatory networks may need the same type of microbial exposures early in life that have been part of the human environment for all of our evolutionary history to function optimally in adulthood," said McDade, also a member of Northwestern's Cells to Society (C2S).

The Northwestern study is the first research on microbial effects on inflammatory systems in infancy that relate in later life to diseases associated with aging. Advancing the scientific literature on the developmental origins of disease, the study arguably is the most significant research on long-term effects of early environments on human physiological function and health in adulthood.

The research took advantage of a longitudinal study of Filipinos, following participants in utero through 22 years of age, to get a better understanding of how environments early in life affect production of C-reactive protein (CRP) production in adulthood.

Levels of the protein rise in the blood due to inflammation, an integral part of the immune system's fight against infection. CRP research mostly has centered on the protein as a predictor of heart disease, independent of lipids, cholesterol and blood pressure, though researchers still dispute that association. Researchers have been looking at excess body fat as a primary source of pro-inflammatory cytokines that produce CRP and behavioral factors related to diet, exercise and smoking. And the CRP research largely has been conducted in relatively affluent settings, such as in the United States, with low levels of infectious diseases.

The Northwestern researchers were interested in what CRP production looks like in the Philippines, a population with a high level of infectious diseases in early childhood compared to Western countries. Relative to Western countries, the Philippines also has relatively low rates of obesity and cardiovascular diseases, consistent with the Northwestern research findings.

Blood tests showed that C-reactive protein was at least 80 percent lower for study participants in the Philippines when they reached young adulthood, relative to their American counterparts, though the Filipinos suffered from many more infectious diseases as infants and toddlers. Filipino participants in their early 20s had average CRP concentrations of .2 milligrams per liter -- five to seven times lower than average CRP levels for Americans. CRP concentrations for Americans in their early 20s were on average around 1 to 1.5 milligram per liter.

"Early Origins of Inflammation: Microbial Exposures in Infancy Predict Lower Levels of C-reactive Protein in Adulthood," will be published online December 9 in the journal Proceedings of the Royal Society B: Biological Sciences. Besides Northwestern's McDade, the co-authors are Julienne Rutherford, University of Illinois at Chicago; Linda Adair, University of North Carolina, Chapel Hill; and Christopher Kuzawa, associate professor of anthropology in Weinberg at Northwestern.

The Northwestern study drew its data from a longitudinal study that began in the early 1980s with 3,327 Filipino mothers in the third trimester of pregnancy. The mothers were interviewed for behaviors related to care giving, and breast feedings were recorded. The household environment was assessed in terms of socioeconomic resources, hygiene (whether domestic animals, such as pigs and dogs, roamed freely) and density of inhabitants.

Researchers visited with the mothers at the delivery of their infants and subsequently every two months for the first two years of the children's lives. Thereafter, the researchers followed up with the children every four or five years until they reached their early 20s. The records they kept on the children include data on infectious diseases, growth in height and weight.

"In the U.S we have this idea that we need to protect infants and children from microbes and pathogens at all possible costs," McDade concluded.

"But we may be depriving developing immune networks of important environmental input needed to guide their function throughout childhood and into adulthood. Without this input, our research suggests, inflammation may be more likely to be poorly regulated and result in inflammatory responses that are overblown or more difficult to turn off once things get started."

Related Stories

Researchers who have followed 5,840 people from before birth to the age of 31 have found evidence suggesting that small size at birth and excessive weight gain during adolescence and young adulthood may lead to low grade ...

Lower weight at birth may increase inflammatory processes in adulthood, which are associated with chronic diseases such as heart disease and diabetes, according to a new study accepted for publication in The Endocrine Society's ...

Two new studies provide evidence that differences in people’s blood levels of C reactive protein (CRP) stem in part from natural variation in known metabolic genes. The researchers report their findings in the May American Jo ...

People with high levels of a protein called C-reactive protein (CRP), a marker for inflammation in the blood, may be at higher risk for heart attack and death but not stroke, according to a study published in the October ...

Scientists report that a protein best known as a common marker of inflammation plays a key role in the progression of human cancer. The research, published by Cell Press in the September issue of the journal Cancer Cell, ...

Breastfed babies are less likely to have certain cardiovascular disease (CVD) risk factors in adulthood than their bottle-fed counterparts, researchers reported at the American Heart Association’s Scientific Sessions 2007.

Recommended for you

New assays can detect malaria parasites in human blood at very low levels and might be helpful in the campaign to eradicate malaria, reports a study published this week in PLOS Medicine. An international team l ...

Gastric bypass and similar stomach-shrinking surgeries are a popular option for obese patients looking to lose weight or treat type 2 diabetes. While the surgeries have been linked to a decreased risk in many types of cancers, ...

Two hearts, said Keats, can beat as one; but a study led by Weizmann Institute scientists in collaboration with researchers from the University of Pennsylvania shows that sometimes a single heart muscle cell ...

New research from the University of Virginia School of Medicine has shed light on how chronic stress and obesity may contribute to type 2 diabetes. The findings point the finger at an unexpected biological perpetrator – ...

Collaborating with scientists from New York, Toronto, and Tokyo, Harvard Stem Cell Institute (HSCI) researchers have devised two methods for using stem cells to generate the type of neurons that help regulate ...

Treatment for painful episodes of blood vessel obstruction in sickle cell anemia is currently limited to controlling pain, but an investigational therapy might be able to interfere with the underlying cause of these events, ...

Like your great grandmother probably said " You've got to eat your peck of dirt before you die." or, more recently, "Children are to be given a "dirt pill" to provide the germs they missed out on as toddlers as part of a revolutionary treatment for asthma. Researcher Susan Prescott said asthmatic children would receive daily medication that would include a mixture of different strains of probiotic bacteria and antioxidants.—Ean Higgins, "Dirt pills may help to ease kids' asthma," The Australian, April 27, 2006"

My Bro-in-law worked inside what was the highest level and size clean lab in Canada, about 15 years back.

He said they had to get outside and get dirty, twice a day. Otherwise, their immune systems would shut down on them and they would be open to infectious situations.

This is what the lab owners had them do, twice a day: Get out, encounter some germs and dirt, please.

The empirical evidence from clean lab use indicated this exact aspect when such clean labs began to come on line in a big way. So now we have a 'study' that shows this point that clean lab folks have known for decades, now.

Please sign in to add a comment.
Registration is free, and takes less than a minute.
Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.

Javascript is currently disabled in your web browser. For full site functionality, it is necessary to enable Javascript.
In order to enable it, please see these instructions.